Remote control systems that can distinguish stray light sources

ABSTRACT

Remote control systems that can distinguish predetermined light sources from stray light sources, e.g., environmental light sources and/or reflections are provided. The predetermined light sources can be disposed in asymmetric substantially linear or two-dimensional patterns. The predetermined light sources also can be configured to exhibit signature characteristics. The predetermined light sources also can output light at different signature wavelengths. The predetermined light sources also can emit light polarized in one or more predetermined polarization axes. Remote control systems of the present invention also can include methods for adjusting an allocation of predetermined light sources and/or the technique used to distinguish the predetermined light sources from the stray light sources.

CROSS-REFERENCE TO RELATED CASES

This application is a divisional of U.S. patent application Ser. No.11/803,674, filed on May 14, 2007, which is incorporated herein byreference in its entirety. This application is related to U.S. patentapplication Ser. No. 11/594,313, filed on Nov. 7, 2006, Attorney DocketNo. P4736US1, now U.S. Pat. No. 7,566,858, which is incorporated hereinby reference in its entirety.

FIELD OF THE INVENTION

The present invention can relate to remote control systems that candistinguish one or more predetermined light sources from stray lightsources.

BACKGROUND OF THE INVENTION

Some remote control systems use infrared (IR) emitters to determine theposition and/or movement of a remote control. For example, if IRemitters are mounted proximate to a television, the remote control maybe able to detect its own motion by measuring the relative motion of theIR emitters with respect to the remote control.

Such systems, however, may not be able to distinguish desired orpredetermined IR light sources from undesirable environmental IRsources, e.g., the sun or a light bulb. Because those systems maymistakenly identify unintended environmental IR sources as intended IRemitters, the systems may incorrectly determine the position and/ormovement of the remote control.

Such systems also may experience another common problem in that thesystems may not be able to distinguish IR emitters from reflections ofthe IR emitters, e.g., from the surface of a table or a window. Forexample, when IR emitters are disposed in a pattern that is symmetricalabout a horizontal axis, the remote control system may mistakereflections of the IR emitters from a table surface for the actual IRemitters. Or, when IR emitters are disposed in a pattern that issymmetrical about a vertical axis, the remote control system may mistakereflections of the IR emitters from a window for the actual IR emitters.Again, such mistakes may result in incorrect determinations of theposition and/or movement of the remote control.

SUMMARY OF THE INVENTION

The present invention relates to remote control systems that candistinguish predetermined light sources from stray or unintended lightsources, such as environmental light sources and/or reflections.

In one embodiment of the present invention, the predetermined lightsources can be disposed in asymmetric substantially linear ortwo-dimensional patterns. Here, a photodetector can detect light outputby the predetermined light sources and stray light sources, and transmitdata representative of the detected light to one or more controllers.The controllers can identify a derivative pattern of light sources fromthe detected light indicative of the asymmetric pattern in which thepredetermined light sources are disposed.

In another embodiment of the present invention, the predetermined lightsources can output waveforms modulated in accordance with signaturemodulation characteristics. By identifying light sources that exhibitthe signature modulation characteristics, a controller can distinguishthe predetermined modulated light sources from those that do notmodulate in that same way.

In another embodiment of the present invention, each predetermined lightsource can output light at one or more different signature wavelengths.For example, a photodetector module of the present invention can detectthe signature wavelengths using multiple photodetectors, each of whichcan detect one of the signature wavelengths. Alternatively, thephotodetector module can include an interleaved photodetector having anarray of interleaved pixels. Different portions of the interleavedpixels can detect one of the signature wavelengths.

In yet another embodiment of the present invention, a display can have amatrix of pixels having one or more signature pixels. The signaturepixel(s) can exhibit one or more signature characteristics thatdistinguish the signature pixel(s) from the other pixels in the matrixand from other light sources that do not exhibit the signaturecharacteristic(s). For example, the signature pixel(s) can exhibit oneor more signature modulation characteristics, wavelengths, polarizationaxes, intensities, shapes, etc. The present invention also can includemethods for adjusting the allocation of signature pixels in the displaybased on data indicative of conditions under which a photodetectordetects the signature pixels.

In another embodiment of the present invention, a light transmitter canbe configured to transmit light that is polarized. For example, thelight can have one or more predetermined polarization axes. Based on themeasured intensity of light received by one or more complementaryphotodetectors, a controller can distinguish the polarized light fromunpolarized stray sources.

The present invention also can include methods for adjusting thetechnique used for distinguishing predetermined light sources from straylight sources. The adjustment can be based on data indicative of one ormore conditions under which a photodetector is detecting light emittedfrom the predetermined light sources.

Combinations of the embodiments described herein also are within thescope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages of the present invention will be apparentupon consideration of the following detailed description, taken inconjunction with accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIG. 1 illustrates one embodiment of a remote control system of thepresent invention having an asymmetric pattern of predetermined lightsources;

FIG. 2 illustrates a process for distinguishing predetermined lightsources from stray light sources based on the pattern in which the lightsources are disposed in accordance with one embodiment of the presentinvention;

FIGS. 3A-3E illustrate additional embodiments of asymmetric patterns ofpredetermined light sources in accordance with the present invention;

FIG. 4 illustrates a remote control system of one embodiment of thepresent invention that can distinguish predetermined light sources fromstray light sources based on signature modulation characteristics withwhich output waveforms of the predetermined light sources are modulated;

FIG. 5 illustrates a process of one embodiment of the present inventionfor distinguishing predetermined light sources from stray light sourcesbased on signature modulation characteristics with which outputwaveforms of the predetermined light sources are modulated;

FIGS. 6A-6B illustrate interleaved photodetectors in accordance with oneembodiment of the present invention;

FIGS. 7A-B show an illustrative display having one or more integratedsignature pixels, the output of which can be used to measure relativecontroller motion, such as by modulation, polarization, etc., inaccordance with one embodiment of the present invention;

FIG. 7C illustrates a process for adjusting the allocation of signaturepixels in the display of FIGS. 7A-B based on data indicative ofconditions under which a photodetector is detecting light emitted fromthe signature pixels in accordance with one embodiment of the presentinvention;

FIG. 8A shows an illustrative remote control system configured todistinguish one or more predetermined light sources from stray lightsources by generating and detecting light at one or more predeterminedpolarization axes in accordance with one embodiment of the presentinvention;

FIG. 8B shows four illustrative predetermined light sources that emitlight in four illustrative predetermined polarization axes in accordancewith one embodiment of the present invention;

FIGS. 8C-8F show illustrative relative intensities of light aphotodetector can expect to receive from the illustrative predeterminedlight sources of FIG. 8B when a remote control rolls about the z-axisand the relative locations from which those predetermined light sourcescan be expected to emit the light in accordance with one embodiment ofthe present invention; and

FIG. 9 shows an illustrative process for adjusting the technique used bya remote control system for distinguishing predetermined light sourcesfrom stray light sources in accordance with one embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention can include remote control systems that candistinguish predetermined light sources from stray light sources, suchas environmental light sources and/or reflections.

FIG. 1 illustrates one embodiment of a remote control system of thepresent invention. Remote control system 10 can include remote control12 and multiple predetermined light sources 16. Predetermined lightsources 16 can be disposed in frame 18 to form light transmitter 14 orintegrated with display 20. As used herein, light sources can eithergenerate light or reflect light shined thereon. If light source(s) actas reflector(s), another light source can project light towards thereflector(s). The reflector(s) can reflect the light back to aphotodetector. For example, the photodetector and the other light sourcecan be disposed on remote control 12, whereas the reflector(s) can bedisposed proximate to, near, on, or in display 20.

Remote control system 10 can permit a user to interact with an imageshown on display 20 by manipulating remote control 12. Display 20 canproject an image substantially defined by orthogonal x- and y-axes.Display 20 can include a television having a screen with a nominalcurvature, a computer monitor having a screen with a nominal curvature,a flat-screen television, a flat-screen monitor, a surface upon which aprojector can project images, or any other type of display known in theart or otherwise.

Remote control system 10 can permit a user to move or otherwise selectobject 19 (e.g., a cursor) shown on display 20 in the x- and y-axes bypointing remote control 12 at desired locations on or proximate todisplay 20. Ray R can indicate the location at which remote control 12is pointing. Remote control system 10 can detect the remote control'smotion by measuring the motion of predetermined light sources 16 withrespect to its own. Based on the detected motion, remote control system10 can determine the absolute x- and y-positions of the location towhich the remote control is pointing with respect to one or morereference locations, e.g., one or more of the predetermined lightsources. Remote control system 10 then can be used to move object 19 tothe determined location. Thus, when the user moves remote control 12 inthe x- and y-axes, display 20 can show a corresponding movement inobject 19 in the x- and y-axes.

Predetermined light sources 16 can emit, e.g., infrared (IR) light 22 toremote control 12. Remote control 12 can detect the emitted light usingphotodetector 24. Photodetector 26 can include CCD arrays, CMOS arrays,two-dimensional position sensitive photodiode arrays, other types ofphotodiode arrays, other types of light detection devices known in theart or otherwise, or a combination thereof.

In accordance with the present invention, predetermined light sources 16can be spatially constrained in an asymmetric substantially linearpattern in frame 18. The substantially linear pattern can be parallel toa longitudinal axis of transmitter 14 and asymmetric about an axisorthogonal to the longitudinal axis of transmitter 14. For example, asshown in FIG. 1, remote control system 10 can include threepredetermined light sources 16 disposed in a substantially linearpattern. The distance between left-most predetermined light source 16 aand middle predetermined light source 16 b can be less than that betweenmiddle predetermined light source 16 b and right-most predeterminedlight source 16 c. While FIG. 1 illustrates three predetermined lightsources, remote control system 10 can include four or more predeterminedlight sources disposed in an asymmetric substantially linear pattern.

Predetermined light sources 16 can be disposed proximate any edge ofdisplay 20, e.g., a top, bottom, or vertical edge of display 20 eitherin frame 18 or integrated with display 20. Predetermined light sources16 also can be disposed substantially co-planar with the screen of thedisplay. Alternatively, transmitter 14 and/or predetermined lightsources 16 can be disposed at another location near, on, or beneathdisplay 20.

Remote control system 10 also can include controller 26, which can bedisposed in remote control 12. Controller 26 can accept datarepresentative of light detected by photodetector 24. In a mannerdescribed in greater detail below with respect to FIG. 2, controller 26can distinguish predetermined light sources from stray light sourcesusing the photodetector data. The controllers described herein caninclude processors, memory, ASICs, circuits and/or other electroniccomponents.

Remote control 12 also can incorporate user input component 28. A usermay actuate user input component 28 when the user wants remote controlsystem 10 to perform an action. For example, a user may actuate userinput component 28 when the user is moving remote control 12 and wantsobject 19 to reflect similar motion on display 20. When the user is notactuating user input component 28, remote control system 10 can beconfigured to take no action.

User input component 28 can be a scrollwheel similar to thatincorporated by a portable media player sold under the trademark iPod™by Apple Inc. of Cupertino, Calif. The scrollwheel can include one ormore buttons and a touchpad or other input device. The touchpad canpermit a user to scroll through software menus by running the user'sfinger around the track of the scrollwheel. User input component 38 alsocan include, for example, one or more buttons, a touchpad, a touchscreendisplay, or a combination thereof.

Remote control system 10 also can include optional console 30. Console30 can have controller 32 that can perform some or all of the processingdescribed for controller 26. For example, remote control 12 can transmitdata representing detected IR light 22 to console 30. Controller 32 inconsole 30 then can identify predetermined light sources 16 from thelight sources detected by photodetector 24.

In one embodiment of the present invention, console 30 can communicatewith remote control 12 using cable 34 and/or one or more wirelesscommunication protocols known in the art or otherwise. Console 30 alsocan communicate with transmitter 14 using cable 35 and/or one or morewireless communication protocols known in the art or otherwise. Console30 also can communicate with display 20 using cable 36 and/or one ormore wireless communication protocols known in the art or otherwise.Alternatively, console 30 can be integrated with display 20 as one unit.

Console 30 also can have one or more connectors to which accessories canbe coupled. Accessories can include cables, game cartridges, portablememory devices (e.g., memory cards, external hard drives, etc.),adapters for interfacing with another electronic device (e.g.,computers, camcorders, cameras, media players, etc.), or combinationsthereof.

FIG. 2 illustrates one embodiment of a process that controller 26 or 32can employ to distinguish predetermined light sources from stray lightsources based on the pattern in which the predetermined light sourcesare disposed. In step 40, controller 26 or 32 can accept datarepresentative of light detected by photodetector 24. In step 42,controller 26 or 32 can identify a plurality of (e.g., all) points ofinterest (POIs) or detected light sources from the photodetector data,regardless of whether the light source is one of predetermined lightsources 16 or a stray light source. Identification of a POI can includedetermining positional characteristics of the detected light source. Asused herein, the “positional characteristics” of a light source or groupof light sources can include characteristics that indicate the absoluteor relative position and/or geometry of the light source(s), e.g., theabsolute x- and y-positions of the light source(s).

To determine the absolute x- and y-positions of the light sourcesdetected by photodetector 24, controller 26 or 32 can use any availabletechniques known in the art. For example, U.S. Pat. No. 6,184,863 toSibert et al., issued on Feb. 6, 2001, and No. 7,053,932 to Lin et al,issued on May 30, 2006, the entireties of which are incorporated hereinby reference, describe two techniques that can be employed by controller26 or 32. U.S. Patent Application Publication No. 2004/0207597 to Marks,published on Oct. 21, 2004; No. 2006/0152489 to Sweetser et al.,published on Jul. 13, 2006; No. 2006/0152488 to Salsman et al.,published on Jul. 13, 2006; and No. 2006/0152487 to Grunnet-Jepsen etal., published on Jul. 13, 2006, the entireties of which also areincorporated herein by reference, describe additional techniques thatcan be employed by controller 26 or 32. Remote control system 10 alsocan employ other techniques known in the art or otherwise.

In step 44, controller 26 or 32 can identify a plurality of (e.g., allpossible) permutations of the light sources identified in step 42. Eachpermutation can contain the same number of light sources as the numberof predetermined light sources. In the illustrative embodiment of FIG.1, controller 26 or 32 can identify a plurality of (e.g., all possible)triads, which can be sets of three POIs identified in step 42. In step46, controller 26 or 32 can correlate the pattern formed by eachpermutation or triad identified in step 44 to the asymmetric pattern inwhich predetermined light sources 16 are disposed. Correlationtechniques can include statistical techniques, e.g., Chi-square test,least-squares test, or another correlation technique known in the art orotherwise. Controller 26 or 32 can quantify the correlation bydetermining a correlation coefficient for each permutation or triad.Each correlation coefficient can indicate how well the pattern formed byeach permutation matches the pattern formed by the predetermined lightsources.

When a user is manipulating remote control 12, the remote control maynot be aligned with predetermined light sources 16 in such a way thatany of the permutations or triads identified in step 44 will have apattern that perfectly matches the asymmetric pattern in whichpredetermined light sources 16 are disposed. Accordingly, in correlatingthe pattern formed by each permutation or triad identified in step 44 tothe asymmetric pattern of predetermined light sources 16, controller 26or 32 can account for perceived translation, roll, and/or scaling of theasymmetric pattern in the x- and/or y-axes. As used herein, roll of apattern of predetermined light sources may refer to the rotation of thepattern about an axis orthogonal to the x- and y-axes. Scaling of apattern of predetermined light sources may refer to the enlargement orreduction of the pattern in the x- and/or y-axes.

In step 48, controller 26 or 32 can identify a predetermined number of Npermutations or triads that form patterns that approximate theasymmetric pattern in which predetermined light sources 16 are disposed.Assuming that the correlation coefficients determined in step 46increase the closer the pattern formed by a permutation correlates tothe pattern in which predetermined light sources 16 are disposed,controller 26 or 32 can identify permutations having the bestcorrelation by identifying permutations having the highest correlationcoefficients. However, if the correlation coefficients determined instep 46 decrease the closer the pattern formed by a permutationcorrelates to the pattern in which predetermined light sources 16 aredisposed, controller 26 or 32 can identify permutations having the bestcorrelation by identifying permutations having the lowest correlationcoefficients.

In step 50, controller 26 or 32 can compare the positionalcharacteristics of each permutation or triad identified in step 48 with“good” values determined in previous solutions. Positionalcharacteristics compared in step 50 may include, e.g., the x-position ofeach POI, y-position of each POI, perceived translation of the patternformed by predetermined light sources 16, perceived roll of the patternformed by predetermined light sources 16, and/or perceived scaling ofthe pattern formed by predetermined light sources 16. Based on thecomparison performed in step 50, controller 26 or 32 can identify the“winning” permutation or triad that most likely corresponds topredetermined light sources 16 in step 52.

In one embodiment of the present invention, controller 26 or 32 canidentify in step 48 the permutation having the best correlation (i.e.,N=1). In this case, steps 50 and/or 52 may be unnecessary.

As discussed above, remote control 12 may not be aligned withpredetermined light sources 16 in such a way that the pattern of the“winning” permutation will perfectly match the asymmetric pattern inwhich predetermined light sources 16 are disposed. Instead, the patternof the “winning” permutation may be a derivative indicative of theasymmetric pattern in which predetermined light sources 16 are disposed.For example, the derivative pattern of the “winning” permutation may betranslated, rotated, and/or scaled with respect to the asymmetricpattern in which predetermined light sources 16 are disposed.

In one embodiment of the present invention, controller 26 or 32 cancontinuously reiterate steps 40-52 for each frame of data collected byphotodetector 24. However, there may not be a need to distinguishpredetermined light sources 16 from stray light sources with each frameof data collected by photodetector 24. In the latter case, controller 26or 32 can be configured to only perform steps 40-52 for every Jth frameof data collected by photodetector 24, wherein J is a predeterminednumber. For example, after controller 26 or 32 performs step 44, thecontroller can be configured to determine whether photodetector 24 hascollected J frames of data (step 54). If photodetector 24 has collectedJ frames of data, controller 26 or 32 then can perform step 46 asdescribed above. However, if photodetector 24 has not collected J framesof data yet, controller 26 or 32 can jump to step 50. That is,controller 26 or 32 can compare positional characteristics of eachpermutation or triad identified in step 44 with “good” values determinedin previous solutions. Based on the comparison performed in step 50,controller 26 or 32 can identify the “winning” permutation that mostlikely corresponds to predetermined light sources 16 in step 52.

FIGS. 3A-3C illustrate alternative asymmetric patterns in which todispose predetermined light sources in accordance with the presentinvention. Similar to the embodiment of FIG. 1, predetermined lightsources 62 of FIGS. 3A-3C also can be disposed in frame 64 to formtransmitter 60 or integrated with display 20. In the embodiments ofFIGS. 3A-3C, however, predetermined light sources 62 can be spatiallyconstrained in a two-dimensional pattern that is asymmetric aboutlongitudinal axis L and/or an axis orthogonal thereto.

For example, as shown in FIG. 3A, predetermined light sources 62 can bedisposed in a two-dimensional pattern that is asymmetric aboutlongitudinal axis L. This configuration may be useful to assist remotecontrol system 10 in distinguishing predetermined light sources 62 fromreflections of the predetermined light sources from a surface disposedparallel to longitudinal axis L, e.g., a table surface.

As shown in FIG. 3B, predetermined light sources 62 can be disposed in atwo-dimensional pattern that is asymmetric about an axis orthogonal tolongitudinal axis L. This configuration may be useful to assist remotecontrol system 10 in distinguishing predetermined light sources 62 fromreflections of the predetermined light sources from a surface disposedparallel to an axis orthogonal to longitudinal axis L, e.g., a window.

As shown in FIG. 3C, predetermined light sources 62 can be disposed in atwo-dimensional pattern that is asymmetric about both longitudinal axisL and an axis orthogonal thereto.

FIGS. 3D-3E illustrate alternative asymmetric patterns in whichpredetermined light sources can be spatially constrained in accordancewith the present invention. Predetermined light sources 72 can bedisposed on frames 74 a-74 d, which in turn can be disposed proximate tothe edges of display 20, e.g., top, bottom, and/or vertical edges.Alternatively, predetermined light sources 72 can be integrated intodisplay 20 proximate to the edges of display 20. Advantageously, whenpredetermined light sources are disposed proximate to top and bottomedges of display 20, remote control system 10 can detect a greater rangeof vertical motion.

When disposed proximate to display, predetermined light sources 72 canform a two-dimensional pattern that can be asymmetric about an axisparallel and/or orthogonal to the direction of gravity. This is not tosay that each group of predetermined light sources 72 disposed proximateto each edge of display 20 needs to form a two-dimensional patternand/or be asymmetric about an axis parallel and/or orthogonal to thedirection of gravity. For example, in FIG. 3D, predetermined lightsources 72 a can form a symmetric two-dimensional pattern andpredetermined light sources 72 b can form an asymmetric one-dimensionalpattern. In FIG. 3E, predetermined light sources 72 c and predeterminedlight sources 72 d each can form an asymmetric substantially linearpattern. Indeed, the pattern formed by predetermined light sources 72 dcan be the same pattern formed by predetermined light sources 72 c, butrotated 180 degrees. Advantageously, each of the illustrative patternsformed by the predetermined light sources in FIGS. 3D and 3E may beuseful in assisting remote control system 10 to distinguish thepredetermined light sources from reflections of the predetermined lightsources from surfaces disposed both parallel and orthogonal to thedirection of gravity.

Asymmetric arrangements of predetermined light sources, whether insubstantially linear or two-dimensional patterns, also can permit remotecontrol system 10 to determine whether remote control 12 is upside-downor not. For example, if a remote control system employs a symmetricalpattern of IR emitters, the controller may not be able to distinguishwhether a user is holding the remote control with, e.g., user inputcomponent 28 pointing in the positive y-direction or in the negativey-direction. By disposing predetermined light sources 16 in anasymmetric pattern, a controller of the present invention candistinguish between these configurations by comparing the locations ofthe detected predetermined light sources relative to each other.

In accordance with another aspect of the present invention, remotecontrol systems can modulate output waveform(s) of one or morepredetermined light sources in accordance with one or more predeterminedor signature modulation characteristics. For example, genres ofsignature modulation characteristics can include, e.g., frequency, dutycycle, phase shift, another pulse train signature, or a combinationthereof. For example, the remote control system can continuously turntwo predetermined light sources ON and OFF at first and secondpredetermined frequencies or otherwise adjust the signal strengths ofthe two predetermined light source output waveforms at the predeterminedfrequencies. The first and second frequencies can have the same value ordifferent values. The remote control system can distinguishpredetermined light sources that output modulated waveforms from straylight sources by identifying light sources that exhibit the signaturemodulation characteristics.

FIG. 4 illustrates one embodiment of remote control system 80 of thepresent invention that can distinguish predetermined light sources fromstray light sources by identifying light sources that exhibit, e.g., thesignature frequencies at which predetermined light source waveforms maybe modulated. Transmitter 81 can include first and second predeterminedlight sources 82 a and 82 b and one or more frames 84 on which thepredetermined light sources are disposed. Modulator(s) 85 canfrequency-modulate output of predetermined light sources 82 a and 82 bso that the predetermined light sources are turned ON and OFF atfrequencies f1 and f2 (respectively). Alternatively, modulator(s) 85 canfrequency-modulate the output of the predetermined light sources so thatthe signal strengths of the outputs are otherwise adjusted in apredetermined manner at frequencies f1 and f2. In one embodiment of thepresent invention, light output from predetermined light sources 82 aand 82 b can be modulated at predetermined frequencies that may be lesslikely to be encountered in a user's environment, e.g., between 100 KHzand 300 KHz, inclusive.

Remote control 86 can include photodetector 88 and controller 90. In oneembodiment of the present invention, photodetector 88 can be atwo-dimensional position sensitive diode (PSD). In the embodiment ofFIG. 4, frequencies f1 and f2 can have different values that are greaterthan the frame rate at which photodetector 88 captures data.

Controller 90 can include first and second frequency demodulators 92 aand 92 b, each of which can demodulate the photodetector data inaccordance with one of the signature frequencies at which predeterminedlight sources 82 a and 82 b may be modulated. Demodulator 92 a canaccept output from photodetector 88 and extract the x- and y-positionsof predetermined light source 82 a with respect to remote control 86.Likewise, demodulator 92 b can accept output from photodetector 88 andextract the x- and y-positions of predetermined light source 82 b withrespect to remote control 86. In alternative embodiments of the presentinvention, controller 90 can be disposed in a console, e.g., console 30of FIG. 1, or within display 20.

While FIG. 4 illustrates transmitter 81 with two predetermined lightsources, one of the predetermined light sources can be eliminated oradditional predetermined light sources can be added. In the latter case,the predetermined light sources can be disposed in an asymmetric orsymmetric pattern. Furthermore, the signature frequency or frequenciesat which the predetermined light sources can be modulated can be slowerthan the frame rate at which a photodetector collects data. In oneembodiment of the present invention, one or more predetermined lightsources can be modulated at a signature frequency on the order of 10 Hz.

In alternative embodiments of the present invention, modulator(s) 85 canmodulate output waveforms of predetermined light sources 82 a and 82 bin accordance with another genre or combinations of genres of signaturemodulation characteristic(s). Demodulators 92 a and 92 b then can beconfigured to demodulate output data from photodetector 88 with respectto those genres of signature modulation characteristic(s). In furtheralternative embodiments of the present invention, the demodulators ofFIG. 4 may be replaced with correction filters.

FIG. 5 illustrates one embodiment of a process that a remote controlsystem of the present invention can employ to distinguish predeterminedlight sources from stray light sources by identifying light sources thatexhibit, e.g., the signature frequencies at which output waveforms ofthe predetermined light sources are modulated. In step 100, thecontroller can accept data representative of light detected by aphotodetector disposed, e.g., in a remote control. In step 102, thecontroller can identify a plurality of (e.g., all) points of interest(POIs) or detected light sources from the photodetector data, regardlessof whether the light source is one of the predetermined light sources ora stray light source. Identification of a POI may include determiningpositional characteristics of each detected light source.

In step 104, the controller can track each POI identified in step 102for a predetermined number of M frames. Thereafter, in step 106, thecontroller can determine a modulation characteristic, e.g., thefrequency, at which the light detected for each POI is modulated overthose M frames. For stray light sources that may not modulate orinfrequently modulates its light output over the M frames, e.g., thesun, the determined frequency may be very low, e.g., approximately zero.

In step 108, the controller can correlate the modulationcharacteristics, e.g., the frequencies, determined in step 106 to thesignature modulation characteristic(s) at which the predetermined lightsources are modulated. The controller can quantify the correlation bydetermining a correlation coefficient for each POI. The correlationcoefficient may indicate how well the modulation characteristicdetermined for each POI in step 106 matches the signature modulationcharacteristic(s) at which waveforms output by the predetermined lightsources are modulated.

In step 110, the controller can identify a predetermined number K ofPOIs having modulation characteristics that approximate the signaturemodulation characteristic(s) at which waveforms output by thepredetermined light sources are modulated. Assuming that the correlationcoefficients determined in step 110 increase the closer a modulationcharacteristic determined in step 106 correlates to one of the signaturemodulation characteristics, the controller can identify POIs having thebest correlation by identifying the POIs having the highest correlationcoefficients. However, if the correlation coefficients determined instep 108 decrease the closer a modulation characteristic determined instep 106 correlates to one of the signature modulation characteristics,the controller can identify POIs having the best correlation byidentifying the POIs having the lowest correlation coefficients.

In step 112, the controller can compare the positional characteristicsof each POI identified in step 110 with “good” values determined inprevious solutions. Based on the comparison performed in step 112, thecontroller can identify the “winning” POIs that most likely correspondto the predetermined light sources in step 114.

In one embodiment of the present invention, the controller cancontinuously reiterate steps 100-114 for each frame of data collected bythe photodetector. However, there may not be a need to distinguish thepredetermined light sources from stray light sources with each frame ofdata collected by the photodetector. In the latter case, the controllercan be configured to only perform steps 100-114 for every Lth frame ofdata collected by the photodetector, wherein L is a predeterminednumber. For example, after the controller performs step 102, thecontroller can be configured to determine whether the photodetector hascollected L frames of data (step 116). If the photodetector hascollected L frames of data, the controller then can perform step 104 asdescribed above. However, if the photodetector has not collected Lframes of data yet, the controller can jump to step 112. That is, thecontroller can compare the positional characteristics of each POIidentified in step 102 with “good” values determined in previoussolutions. Based on the comparison performed in step 112, the controllercan identify the “winning” POIs that most likely correspond topredetermined light sources in step 114.

In addition to or instead of modulating the outputs of predeterminedlight sources at signature frequencies, the remote control system of thepresent invention also can modulate output waveform(s) of one or morepredetermined light sources at signature or predetermined duty cycle(s).Output waveforms can be modulated at different or the same predeterminedduty cycle(s). The remote control system also can incorporate one ormore phase shifts between waveforms output by multiple predeterminedlight sources.

In one embodiment of the present invention, a remote control system canhave two or more predetermined light sources, the output waveforms ofwhich can be modulated in accordance with different signature modulationcharacteristics having different predetermined values or genres.Advantageously, this may permit the remote control system to determinewhether remote control is upside-down. For example, if a remote controlsystem employs a symmetrical pattern of IR emitters, the controller maynot be able to distinguish whether a user is holding the remote controlwith, e.g., a user input component pointing in the positive y-directionor in the negative y-direction. By modulating the predetermined lightsource outputs in accordance with different signature modulationcharacteristics, a controller of the present invention can distinguishbetween these configurations.

In accordance with another aspect of the present invention,predetermined light sources can output light at different signaturewavelengths, e.g., in the IR spectrum. For example, a remote controlsystem of the present invention can include first and secondpredetermined light sources. The first predetermined light source canemit light at first wavelength Al and the second predetermined lightsource can emit light at second wavelength A2. A photodetector module,e.g., disposed in a remote control, can include first and secondphotodetectors. The first photodetector can be configured to detectlight having first wavelength Al and the second photodetector can beconfigured to detect light having second wavelength A2. Alternatively,the photodetector module can be an interleaved photodetector.Advantageously, a remote control system having predetermined lightsources that output light of different wavelengths can permit the remotecontrol system to determine whether a remote control is upside-down.

FIGS. 6A-6B illustrate embodiments of interleaved photodetectors inaccordance with the present invention. Interleaved photodetector 120 canbe a single unit having an array of interleaved pixels 122.Predetermined pixels 122 a of the array can be configured to detectlight having first wavelength Al whereas other predetermined pixels 122b of the array can be configured to detect light having secondwavelength A2. For example, alternating rows of pixels (see FIG. 6A) oralternating columns of pixels can be configured to detect light havingdifferent wavelengths A1 and A2. Alternatively, as shown in FIG. 6B, acheckerboard of pixels can be configured to detect light havingdifferent wavelengths Al and A2. In the embodiments of FIGS. 6A-6B,pixels indicated with hatching may be configured to detect light havingfirst wavelength A1 and pixels indicated without hatching may beconfigured to detect light having second wavelength A2.

FIGS. 7A-B illustrates a display having one or more integrated signaturepixels which can be configured to exhibit signature characteristics.Display 130 can incorporate matrix of pixels 132 for showing an image.Pixels 132 can be arranged in any predetermined configuration (e.g., inrows and columns) and driven by a controller, e.g., control circuitry ora processor (not shown). The controller can be disposed in the displayitself or in a separate control device (e.g., a computer, set-top box,etc.). To reduce the amount of IR light emitted from the display to theviewer, display 130 also can incorporate IR filter 134, which can coverall or some of pixels 132. IR filter 134 can be applied, for example,onto an internally-facing surface of screen 136.

One or more signature pixels 140 can be integrated into matrix of pixels132. The signature pixel(s) can exhibit one or more signaturecharacteristics that, when detected by a complementary photodetector,distinguish the signature pixel(s) from light sources that do notexhibit the same signature characteristics. For example, the lightemitted by one or more of the signature pixels can be modulated inaccordance with one or more signature characteristics, e.g.,frequencies, duty cycles, phase shifts, polarization axes, intensities,etc. The light emitted by one or more of the signature pixels also canhave a signature wavelength. Each signature pixel or multiple signaturepixels also can form one or more signature shapes. For example, asignature pixel can physically have a shape that distinguishes thatsignature pixel from the other pixels in matrix 132, or multiplesignature pixels can form a shape that distinguishes those signaturepixels from the other pixels in matrix 132. In one embodiment, thepredetermined signature shape can include an asymmetric arrangement ofthe signature pixels similar to those described herein with respect toFIGS. 1-3E. The signature pixel(s) also can exhibit combinations ofthese and other signature characteristics.

In one embodiment of the present invention, one or more of signaturepixels 140 can occupy a border position of the matrix. One or more ofpixels 140 also can occupy an internal position of the matrix. Multiplesignature pixels 140 also can be distributed within matrix 132 in anasymmetric pattern similar to those discussed herein with respect toFIGS. 1-3E.

In one embodiment of the present invention, IR filter 134 can have oneor more selective transmission features to facilitate communication ofIR light emitted by signature pixels 140 through the filter. Forexample, IR filter can include holes 138 disposed to permit IR lightgenerated by signature pixels 140 to be emitted from display 130 to aphotodetector (e.g., in a remote control). This can, for example, permittransmission of signature modulated IR light from signature pixels 140without undue attenuation in the signal. IR filter 134 also can have oneor more high-pass filters, low-pass filters, and/or band-pass filtersconfigured to permit transmission of signature wavelength(s) of lightfrom signature pixels 140. IR filter 134 also can have one or morepolarizing filters configured to polarize light emitted from signaturepixels 140 in one or more predetermined polarization axes.

To distinguish signature pixel(s) from other sources of light (includingthe remaining pixels in matrix 132), a remote control similar, forexample, to those described with respect to FIGS. 1-6B can be used.

FIG. 7C illustrates a process for adjusting the allocation of signaturepixels in the display of FIGS. 7A-B based on data indicative ofconditions under which a photodetector is detecting light emitted fromthe signature pixels in accordance with one embodiment of the presentinvention. For example, display 130 can be configured to allocate adefault number and configuration of pixels from matrix 132 to serve assignature pixels 140. In step 142, a controller in display 130 oranother host device can initiate such default allocation of signaturepixels. This can include, for example, determining which pixels inmatrix 132 will exhibit signature characteristics and, in some cases,generating signals that instruct those signature pixels to exhibitsignature characteristics. For example, the default allocation ofsignature pixels can include a predetermined number of signature pixelschosen to form a predetermined shape and emit light modulated inaccordance with predetermined modulation characteristics.

In step 144, the controller can accept data indicative of the conditionsunder which a complimentary photodetector (e.g., in a remote control) isdetecting light emitted from the signature pixels. Such data can includeone or more of the following: ambient light data, data indicative of theproximity of the predetermined light sources (e.g., signature pixels) tothe photodetector, data indicative of the signal-to-noise ratio, dataindicative of the image being shown by the remaining pixels in matrix132, data from a user indicative of the preferred allocation ofsignature pixels, etc. One or more sensors can be used to generate someor all of the data accepted in step 144.

In step 146, the controller can identify another subset of signaturepixels having a more optimal allocation based on the data gathered instep 144. For example, the controller can determine that more or lesspixels of matrix 132 should serve as signature pixels. The controlleralso can determine that the signature pixels should occupy differentlocations in matrix 132. For example, if the data indicates that thesignal-to-noise ratio is low, the controller may determine thatadditional pixels from matrix 132 need to serve as signature pixels.Thereafter, in step 148, the controller can generate signals thatinstruct those additional pixels to exhibit one or more signaturecharacteristics. Alternatively, if the data indicates that thesignal-to-noise ratio is high, the controller may determine that one ormore of the signature pixels is unnecessary. Thereafter, in step 148,the controller can generate signals for driving those pixels to show animage on the display along with the remaining pixels in matrix 132,rather than exhibit any signature characteristics.

The controller also may determine that a predetermined signature shapeformed by the signature pixels in matrix 132 may be inappropriate basedon the data collected in step 144. For example, the predetermined shapemay be similar to an image shown on display 130 by the remaining pixelsin matrix 132 or similar to the shape formed by another light source inthe external environment. Responsive to such determination, thecontroller can identify a set of pixels having a different, more optimalconfiguration to serve as the signature pixels and, in step 148,generate signals to initiate that more optimal configuration.

The controller can perform steps 144-148 when it is triggered bypredetermined events that can occur during operation of a remote controlsystem (e.g., each time the system is turned ON or exits a low-powerstate). Alternatively, the controller can be configured to perform steps144-148 at predetermined intervals or continuously during the entiretime the remote control system is in operation.

FIG. 8A shows an illustrative remote control system configured todistinguish one or more predetermined light sources from stray lightsources by generating and detecting light at one or more predeterminedpolarization axes in accordance with one embodiment of the presentinvention. Light transmitter 150 can incorporate, for example,controller 152 and one or more predetermined light sources 154.Controller 152 can generate signals for instructing predetermined lightsources 154 to emit light PL at one or more predetermined intensities.To emit polarized light, light source 154 can be a coherent ornon-coherent light source (e.g., laser, LED, etc.) and a polarizingfilter (not shown) can be used.

Remote 156 can be configured to distinguish predetermined light sources154 from stray light sources by identifying the light sources that emitlight polarized at the predetermined polarization axis or axes. Remote156 can be equipped, for example, with one or more polarizing filters158 disposed over photodetector 160. The polarizing filters can havepolarization axes that have an orientation or orientations thatcomplement (e.g., match) the polarization axes of the light emitted bylight transmitter 150. Polarizing filters 158 can filter out light wavesthat are not polarized in accordance with its polarization axis or axes.Controller 162 of remote 156 can then analyze the intensities of thedetected light to distinguish the predetermined light sources from thestray light sources.

Advantageously, when one or more predetermined light sources areconfigured to emit light at one or more predetermined polarization axesand one or more predetermined intensities, controller 162 can determinethe roll of remote control 156 based on the intensity of the lightreceived from the predetermined light sources. For example, if thepredetermined polarization axis aligns with the Y axis, photodetector160 may detect decreasing intensity from light emitted by predeterminedlight source 154 as remote 156 (and thus the orientation of polarizingfilter 158) is rotated out of alignment with the Y-axis towards theX-axis. The amount of roll can be calculated as a function of theintensity.

In one embodiment of the present invention, light source 154 can includetwo or more predetermined light sources configured to emit light at oneor more predetermined polarization axes and at one or more predeterminedintensities. Because the relative polarizations, intensities, andlocations of the predetermined light sources are known, controller 162can distinguish the predetermined light sources from stray light sourcesby identifying the light sources having the expected relativeintensities.

Although FIG. 8A illustrates light transmitter 150 as being anindependent device, light transmitter 150 can be integrated within ahost electronic device, e.g., a display. If the light transmitter isintegrated within a host device, controller 152 can be dedicated tocontrolling light source 154 or combined with another controller in thehost device.

Furthermore, although FIG. 8A illustrates photodetector 160 andpolarizing filter 158 disposed in remote 156, in an alternativeembodiment of the present invention, light transmitter 150 can insteadbe integrated within remote 156 and photodetector 160 and polarizingfilter 158 can be integrated into a host device or be provided as anindependent unit.

FIG. 8B shows four illustrative predetermined light sources that emitlight in four illustrative predetermined polarization axes in accordancewith one embodiment of the present invention. In the illustrativeembodiment shown in FIG. 8B, four predetermined light sources A-D canemit light having polarization axes orientated along the x-axis, at 45°angle with respect to the x- and y-axes, at 135° angle with respect tothe x- and y-axes, and along the y-axis, respectively. The predeterminedlight sources can be disposed, for example, in astructurally-independent light transmitter, in a display, in remotecontrol 156, or in another host device. Complementary photodetector 160and polarizing filter 158 can be disposed, for example, in remotecontrol 156 or another host device. Polarizing filter 158 can have apolarization axis illustratively oriented along the x-axis eitherpermanently (e.g., when the filter is disposed in a immobile hostdevice) or (if incorporated within remote control 156) when the remotecontrol is disposed with user input component 164 pointing in thepositive y-direction.

FIGS. 8C-8F show illustrative relative intensities of lightphotodetector 160 can expect to receive from illustrative predeterminedlight sources A-D of FIG. 8B when remote control 156 rolls about thez-axis and the relative locations from which those predetermined lightsources can be expected to emit the light in accordance with oneembodiment of the present invention. For example, when remote control156 is disposed with user input component 164 pointing in the positivey-axis (FIG. 8C), photodetector 160 can expect to detect a datum levelof 100% light intensity from predetermined light source A after theincoming light is filtered by polarizing filter 158. In comparison tothat datum level and assuming that all predetermined light sources A-Demit substantially the same intensity of light, photodetector 160 canexpect to detect 50% light intensity from predetermined light sources Band C and 0% light intensity from predetermined light source D, afterthe incoming light is filtered by polarizing filter 158. When remotecontrol 156 is disposed with user input component 164 pointing in thenegative x-axis (FIG. 8D), photodetector 160 can expect to detect adatum level of 100% light intensity from predetermined light source D,50% light intensity from predetermined light sources B and C, and 0%light intensity from predetermined light source A.

When remote control 156 is disposed with user input component 164pointing in the negative y-axis (FIG. 8E) or in the positive x-axis(FIG. 8F), photodetector 160 can expect to detect the same relativeintensities of light from predetermined light sources A-D as compared tothose when the remote control 156 is disposed with the user inputcomponent pointed in the positive y-axis and negative x-axis,respectively. However, the oppositely corresponding orientations ofremote control 156 can be distinguished from each other based on therelative locations from which those predetermined light sources can beexpected to emit light. For example, in FIG. 8C, photodetector 160 canexpect to receive light emitted by predetermined light source A from thetop left corner of the group of predetermined light sources. Incomparison, photodetector 160 can expect to receive light emitted bypredetermined light source A from the bottom right corner of the groupof predetermined light sources in FIG. 8E. Similarly, in FIGS. 8D and8F, photodetector 160 can expect to receive light emitted bypredetermined light source D from the bottom left corner and the topright corner of the group of predetermined light sources, respectively.

The oppositely corresponding orientations of remote control 156 also canbe distinguished, for example, by (1) comparing data from the currentdata frame to data from one or more preceding frames; (2) disposing thepredetermined light sources in an asymmetric pattern similar to thosediscussed with respect to FIGS. 1-3E; (3) configuring one or more of thepredetermined light sources to exhibit a different signaturecharacteristic; (4) accepting data from a single or multi-dimensionalaccelerometer or other sensor that can generate data indicative of theorientation of the remote control; or (5) any combination thereof.

While FIGS. 8B-8F illustrate four predetermined light sources, a remotecontrol system of the present invention can include more than fourpredetermined light sources that emit light in one or more predeterminedpolarization axes. Alternatively, one or more of the predetermined lightsources can be eliminated. For example, two or three predetermined lightsources can be configured to emit light in one or more predeterminedpolarization axes. Because the expected relative intensities of lightand the relative locations from which the predetermined light sourcescan be expected to emit the light are known, the remote control systemof the present invention can distinguish the predetermined light sourcesfrom stray light sources.

In an alternative embodiment of the present invention, remote 156 cansimultaneously transmit and receive light from a separate lighttransmitter in accordance with the principles of the present invention.For example, remote 156 can transmit polarized light to a first set ofphotodetector and polarizing filter that are integrated into a hostdevice or provided in an independent unit. Remote 156 also canincorporate its own photodetector and polarizing filter to receivepolarized light from a separate light transmitter disposed, for example,in the same device that houses the first set of photodetector andpolarizing filter.

In accordance with another aspect of the present invention, a remotecontrol system of the present invention can combine two or more of theembodiments described herein. For example, a remote control system ofthe present invention can have multiple predetermined light sourcesdisposed in an asymmetric pattern. The output waveform of one of thepredetermined light sources can be modulated in accordance with one ormore signature modulation characteristics. The remote control system ofthe present invention can be configured to distinguish the predeterminedlight sources from stray light sources using a two step process. First,the remote control system can identify a light source that exhibits thesignature modulation characteristic(s). Second, the remote controlsystem can identify a derivative pattern of light sources that includethe light source identified in the first step and that is indicative ofthe asymmetric pattern in which the predetermined light sources aredisposed.

FIG. 9 shows an illustrative process for adjusting the technique usedfor distinguishing predetermined light sources from stray light sourcesin accordance with one embodiment of the present invention. In oneembodiment, a remote control system can be equipped with the hardwareand software to support multiple techniques for distinguishingpredetermined light sources from stray light sources (e.g., any of thetechniques described herein). Based on data indicative of conditionsunder which the system is detecting the predetermined light sources, thesystem can be configured to adjust the technique used.

In step 170, a controller in a light transmitter, remote control,console, display, and/or other host unit can identify a defaulttechnique for distinguishing predetermined light sources from straylight sources. The default technique may include any one or more of theembodiments described herein with respect to FIGS. 1-8F. In step 172,the controller can initiate the default technique. This can include, forexample, identifying pixels in an asymmetric pattern in a display toserve as signature pixels and/or identifying other predetermined lightsources to be driven to exhibit one or more signature characteristics.This also can include generating signals that instruct those pixelsand/or predetermined light sources to emit light in accordance with thedefault technique.

In step 174, the controller can accept data indicative of one or moreconditions under which the remote control is detecting light emittedfrom the predetermined light sources. Again, such data can include oneor more of the following: ambient light data, data indicative of theproximity of the predetermined light sources to the photodetector, dataindicative of the signal-to-noise ratio, data indicative of the imagebeing shown by a display associated with the predetermined light sourcesor remote control system, data from a user indicative of auser-preferred technique, etc. One or more sensors can be used togenerate some or all of the data accepted in step 174.

In step 176, the controller can identify another technique fordistinguishing predetermined light sources from other light sourcesbased on the data gathered in step 174. For example, if the defaulttechnique results in a low signal-to-noise ratio, the controller maychange the technique employed for distinguishing the predetermined lightsources to attempt to increase the signal-to-noise ratio.

In one embodiment of the present invention, each technique fordistinguishing predetermined light sources that is supported by theremote control system can be associated with one or more conditionsunder which the technique is more suited. For example, one or moretechniques may be better suited for use during the daytime whereas othertechniques may be better suited for use during the evenings. Thus, instep 176, the controller may change the technique employed fordistinguishing the predetermined light sources based on ambient lightdata. Alternatively, one or more techniques may be better suited thanother techniques when the predetermined light sources are located faraway from the photodetector. Thus, in step 176, the controller maychange the technique employed for distinguishing the predetermined lightsources based on data indicative of the proximity of the predeterminedlight sources to the photodetector.

Thereafter, in step 178, the controller can initiate the other techniqueselected in step 176 by, for example, generating drive signals for theappropriate hardware.

The controller can perform steps 170-178 when it is triggered bypredetermined event that can occur during operation of a remote controlsystem (e.g., each time the system is turned ON or exits a low-powerstate). Alternatively, the controller can be configured to perform steps170-178 at predetermined intervals or continuously during the entiretime the remote control system is in operation.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration. Alternative embodiments of thosedescribed hereinabove also are within the scope of the presentinvention. For example, predetermined light sources can be disposed in aremote control and a photodetector can be disposed in a display, in aframe disposed proximate to the display, or at any location proximateto, on, or near a display.

A remote control of the present invention can be any electronic devicein a system that may need to distinguish predetermined light sourcesfrom stray light sources. For example, the remote control can be anyportable, mobile, hand-held, or miniature consumer electronic device.Illustrative electronic devices can include, but are not limited to,music players, video players, still image players, game players, othermedia players, music recorders, video recorders, cameras, other mediarecorders, radios, medical equipment, calculators, cellular phones,other wireless communication devices, personal digital assistances,programmable remote controls, pagers, laptop computers, printers, orcombinations thereof. Miniature electronic devices may have a formfactor that is smaller than that of hand-held devices. Illustrativeminiature electronic devices can include, but are not limited to,watches, rings, necklaces, belts, accessories for belts, headsets,accessories for shoes, virtual reality devices, other wearableelectronics, accessories for sporting equipment, accessories for fitnessequipment, key chains, or combinations thereof.

While the above description may have described certain components asbeing physically separate from other components, one or more of thecomponents can be integrated into one unit. For example, thephotodetector or photodetector module can be integrated with one or morecontrollers.

Also, a controller in the display can perform some or all of theprocessing described above for controllers 26 and/or 32. Thus, multiplecontrollers may be used to control remote control systems of the presentinvention.

Furthermore, while the illustrative remote control systems describedabove may have included predetermined light sources that output lightwaves, one or more of the predetermined light sources can be replacedwith component(s) that output or reflect other types of energy waveseither alone or in conjunction with light waves. For example, thecomponent(s) can output radio waves.

The above described embodiments of the present invention are presentedfor purposes of illustration and not of limitation, and the presentinvention is limited only by the claims which follow.

1.-20. (canceled)
 21. A system comprising: one or more predeterminedlight sources configured to emit light polarized in one or morepredetermined polarization axes; a photodetector for detecting lightfrom light sources, wherein the photodetector is configured to generatephotodetector data; one or more polarizing filters disposed to acceptlight from the light sources before the light is detected by thephotodetector, wherein the one or more polarizing filters are configuredin one or more predetermined polarization axes; and a controllerconfigured to distinguish the one or more predetermined light sourcesfrom other light sources based on the photodetector data.
 22. The systemof claim 21, wherein the one or more predetermined light sourcescomprise multiple predetermined light sources disposed in a pattern thatis asymmetric about at least a first axis.
 23. The system of claim 22,wherein the controller is configured to identify multiple light sourcesfrom the photodetector data that form a derivative pattern indicative ofthe asymmetric pattern.
 24. The system of claim 21, wherein: the one ormore predetermined light sources comprise multiple predetermined lightsources; and the controller is configured to identify multiple lightsources from the photodetector data that exhibit expected relativeintensities.
 25. The system of claim 21, wherein the photodetector, oneor more polarizing filters, and controller are disposed in a remotecontrol.
 26. The system of claim 21, wherein the one or morepredetermined light sources are disposed in a remote control.
 27. Amethod for distinguishing multiple predetermined light sources fromstray light sources, the method comprising: emitting polarized lightfrom the multiple predetermined light sources at one or morepredetermined intensities, wherein the polarized light is polarized inone or more predetermined polarization axes; filtering light from lightsources using one or more polarizing filters; detecting light from thelight sources using a photodetector after the light is filtered by thepolarizing filter; generating photodetector data representative of thedetected light; and identifying multiple light sources from thephotodetector data that exhibit expected relative intensities.
 28. Themethod of claim 27, wherein the multiple predetermined light sources isdisposed in a pattern that is asymmetric about at least a first axis,the method further comprising identifying multiple light sources fromthe photodetector data that form a derivative pattern indicative of theasymmetric pattern.
 29. The method of claim 27, wherein thephotodetector and polarizing filter are disposed in a remote control,the method further comprising generating signals responsive to useractuation of a user input component of the remote control.
 30. Themethod of claim 27, wherein the one or more predetermined light sourcesare disposed in a remote control, the method further comprisinggenerating signals responsive to user actuation of a user inputcomponent of the remote control.
 31. The method of claim 27, whereinemitting polarized light from the multiple predetermined light sourcescomprises emitting polarized light from multiple coherent light sources.32. The method of claim 27, wherein emitting polarized light from themultiple predetermined light sources comprises emitting polarized lightthrough one or more polarizing filters.
 33. A method for identifying atechnique for distinguishing one or more predetermined light sourcesfrom other light sources, the method comprising: accepting dataindicative of one or more conditions under which a photodetector isdetecting light emitted from the one or more predetermined lightsources; and identifying a first technique for distinguishing the one ormore predetermined light sources from the other light sources based onthe data.
 34. The method of claim 33, further comprising initiating thefirst technique by generating signals for controlling hardwareassociated with the first technique.
 35. The method of claim 33, furthercomprising: identifying a second technique for distinguishing the one ormore predetermined light sources from the other light sources, whereinthe second technique comprises a default technique; and changing fromthe second technique to the first technique to distinguish the one ormore predetermined light sources from the other light sources.
 36. Themethod of claim 33, wherein the data comprises ambient light data, dataindicative of the proximity of the one or more predetermined lightsources to the photodetector, data indicative of an image being shown bya display associated with the one or more predetermined light sources,data indicative of a signal-to-noise ratio, data from a user indicativeof a user-preferred technique, or any combination thereof.